This invention is directed to an improved patch and method of repair of the integrity and/or surface imperfections of fiberglass; sheet metal or plastic structures which are defective because of accidental damage or flaws during the course of manufacture or subsequent use and handling. The techniques and methods are also applicable to the manufacture of new original equipment.
It has been known in the art to patch damaged metal and/or fiberglass reinforced polyester objects with fiberglass cloth which has been saturated with either epoxy or polyester/styrene resin compositions. The resulting composites have many disadvantages such that they generally require that the resins be supplied as two separate components which must be premixed just prior to use. After the mixing has been completed the fiberglass cloth must be saturated with the premixed resin and applied rapidly to prevent premature gelation.
The time frame necessary for cure of such epoxys resins is generally measured in hours and/or overnight. When they have finally cured, the cured composites have relatively poor resistance to impact forces since the cured epoxy and polyester/styrene resins are brittle materials that when impacted can produce severe cracking or total failure.
Epoxies, additionally, require an accurate mix ratio of resin and hardeners and a thorough mixing of both for uniform curing. Polyester/styrene compositions require that a small amount of hardener be mixed thoroughly with the resin, typical ratios being about 5:100 respectively. This provides the potential operator errors leading to poor performance of repaired structures.
Laminate patches are well known. For example, in U.S. Pat. No. 3,189,509 in which an imperforate aluminum beaded sheet utilizes an epoxy resin that is initially fluidal to fill the interstices in a discontinuity of a damaged metal panel as well as the space between the beads on the aluminum sheet. A method of repairing discontinuities in fiberglass structures and utilizing either a polyester resin or the inventor's preferred variety of self-curing epoxy resins is clearly shown in U.S. Pat. No. 3,814,645. A laminate patch for interiors which makes use of aluminum sheeting, paper layers and an overlay of plaster is shown in U.S. Pat. No. 4,135,017. A method for repairing plastic materials in which a backing material is utilized to define a specific void behind the damage and then filling the discontinuity is covered in U.S. Pat. No. 3,920,497. The use of repair patches in automotive tires that utilize a first and second series of strips interwoven at right angles to one another and wherein the strips include reinforcing cords and uncured curable elastomers is shown in U.S. Pat. No. 3,730,247.